Egyptian investigators on Friday tested the air conditioning and other appliances in the hotel room that two British tourists who died this week were staying in.

According to a General Prosecutor statement sent to Al Arabiya English, a team of engineers tested “all air-related systems” in the room and they were found to be “safe” and that “no poisonous gas was detected.”

This follows earlier reports in British press that carbon monoxide poisoning was a possible factor in the death of John Cooper, 69, and wife Susan, 63, who became ill and died this week at the Steingenberger Aqua Magic Hotel in Hurghada, about 280 miles south of Cairo.

The statement said that further forensic examination will also take place and a final report will be released.

In its initial report, the forensic team stated that there are no signs of criminal resistance or violence existing on the two bodies.

In a precautionary response, British travel company Thomas Cook pulled more than 300 of its customers from the hotel after an increase in the number of illnesses there.